Automatic floor leveling equipment for elevators



Nov. 28, 1933. F G, ARWOOD 1,937,136

AUTOMATIC FLOOR LEVELING EQUIPMENT FOR ELEVATORS Filed Feb. 5, 1932 2 Sheets-Sheet l L F1 9-1 gave f P-T TL 23 u 119 53 DL vb DOWN Nov. 28, 1933. 1 ARWQQD 1,937,136

AUTOMATIC FLOOR LBVELING EQUIPMENT FOR ELEVATORS Filed Feb. 25. 1932 2 Sheets-Sheet 2 Patented Nov. 28 1933 PATENT OFFICE AUTOMATIC FLOOR LEVELING EQUIPMENT FOR ELEVATORS Fritts G.Arwood, Washington, D. 0., assignor to The Haughton Elevator & Machine Company, Toledo, Ohio, a corporation of Ohio Application February 25, 1932. Serial No. 595,113

6 Claims.

Thisinvention relates-to automatic floor leveling equipment for elevators, which has been designed with the object of insuring accurate response to its actuating means, so as to reduce to 6 a minimum the oscillation of the elevator up and down in the vicinity of a floor landing before it comes to rest within'the required range.

Heretofore in order to insure the satisfactory operation of automatic 2-way fioor leveling equipment, it has been necessary to use it only in connection with a low speed elevator or with the lowest speed of a multi-speed elevator, owing to the appreciable time required for bringing the car to a-stop after the fioor leveling relay has been tripped.

For example, the shortest time in which it is possible to apply magnet-operated brake shoes to the drum is not less than A; second. This operation includes the opening of a switch by the move- 20 ment of the car into the leveling zone, which deenergizes the magnetic switch or relay, the opening of thebrake magnet circuit, and the consequent movement of the brake magnet plunger to apply the brake shoe.- If the normal speed of the car is 120 feet per minute, therefore, or 24 inches'per second, the car will travel 3 inches while the brake shoe is being applied. Assuming that the setting of the floor leveling device calls for a stop within inch of the floor level, the car will continue to oscillate and will not stop at all Within the required accuracy range. In order to overcome the above difiiculties and to insure the required accuracy in leveling without reducing the traveling speed ,of the car, the present invention provides an arrangement whereby the opening of the brake control circuit is independent of the opening of the motor control circuit, so that it is possible, with proper setting, to open the brake control circuit sufficiently in advance to cause the brake shoe to actually engage the'drum approximately at the same time that the motor control circuit is opened.

This invention makes it possible to at least double the leveling speed of the car and still attain the same accuracy in stopping. Consequently, with multi speed elevators it is possible to double thefull or high speed of travel. The invention is of special'value for straight alternating current or rheostatic controlled equipment, because of the limited speed reduction which is possible in such equipment.

For the sake of simplicity in illustrating my invention, I have shown only a single speed alternating current control Without acceleration and without the usual safety features, such as limit switches, emergency switches and the like, since these are well known and may be added without afiecting the operation of the invention.

My invention is adapted to be used in connec-. tion with any standard floor leveler which is controlled by a pliatron relay or by cams in the hatch- Way or by any other means. For the purpose of illustrating and explaining the operation of the invention, it is shown in the accompanying drawings as controlled by cams in the hatchway.

Figure 1 is a diagram of the wiring for the invention.

Figure 2 is side elevation of an elevator with which the invention is associated, and shows a common type of cam actuated leveling means.

Figure 3 is an across-the-line diagram showing substantially the same arrangement as that shown in Figure 1.

In the type of fioor leveler illustrated in Fig. 2, a pivoted arm 5 carried by the elevator car 6 controls the down leveling motor circuit switch, a pivoted arm 7 carried by the elevator car below the arm 5 controls the up leveling motor circuit switch, and a pivoted arm 8 carried by the elevator car, independently of the arms 5 and '7, controls the opening of the brake coil circuit in advance of the motor circuit. As the elevator car, traveling downwardly toward the floor 9, enters the leveling zone, which usually extends 12 to 24 inches both above and below the floor, the roller 10 on the arm 5 rides upon the cam 11 and closes a circuit through the motor while the car switch is in off position. The roller 10 leaves the cam 11 and opens the motor circuit in time to stop the car within the required accuracy range. In order that the brake may be applied at the same instant that the motor circuit is opened, a cam 12 is so located that the roller 13 on arm 8 engages the same to open the brake control circuit in advance of the opening of the motor circuit, the distance being determined of course by the leveling car speed and the time it takes the brake mechanism to operate. Similarly, when the car is traveling upwardly toward the floor 9, the roller 13 first engages the cam 12, and subsequently the roller 14 carried by the arm 7 leaves the cam 15 in time to stop the car within the required accuracy range. ,Within this range the roller 13 still engages the cam 12 but neither of the rollers 10 or 14 engages its cam. It is of course understood that the roller 14 and cam 15 are offset from the roller 10 and cam 11 so that roller 14 never engages the cam 11 and roller 10 never engages the cam 15. In actual practice, it is customary to provide magnets to retire the floor leveling means, whenever the car switch is closed.

Figure 1 illustrates the wiring connections for adapting the invention to an elevator which is operated by alternating current. The current is supplied by the lines L L and L The car switch 20 is moved in one direction to connect the line L through contacts 21 and 22 and down direction coil DC to the line L and is moved in the other direction to connect the line L through contacts 21 and 23 and up direction coil UC to the line L When the car switch is moved to energize either coil DC or UC a circuit is also established through contact 20 and line 24 to energize the coil FC.

One terminal of the motor M is constantly connected to the line L When the coil DC is energized, the switches D are closed and the other two terminals of the motor are connected to the lines L and L respectively for operation in a downward direction. When the coil U0 is energized these other two terminals of the motor are oppositely connected to the lines L and L respectively for operation in an upward direction. When thus operating in either direction, the coil PC is energized to open the normally closed switch Fand cut out the leveling relay circuits 25 and 26.

The leveling device, which is represented at 27, may be actuated by cams, by a pliatron relay, or by any other standard floor leveling trip. As the car enters the leveling zone, if the car switch is in neutral position, the leveling device 27 closes either the switch 28 or 29, depending upon whether the car is above or below the floor. The switch F also closes, whenever the car switch is moved to neutral position.

If the car is traveling upwardly and approaching the floor, the coil ULC is energized and closes the switches UL and UL. The coil UC is then energized, although the car switch is in neutral position, and the motor M is energized for upward travel. Similarly if the car is traveling downwardly and approaching the floor, the coil DLC is energized, closing the switches DL and 15L, the coil DC is energized and the motor M is energized for downward travel. As the car enters the accuracy range, the switch 28 or 29, as the case may be, is opened by the leveling device 27, to stop the operation of the motor.

The device for applying the brake for automatic leveling is indicated at 30 and, as heretofore stated, is actuated independently of the means indicated at 27 for controlling the operation of the motor in leveling. It will be understood that the motor driven hoisting mechanism is equipped with the conventional type of magnetic brake, which is spring set and which is released by the polyphase electromagnet B, whenever the latter is energized. Since the switch BL is normally closed and switch UL is closed whenever switch UL is closed to operate the motor, a circuit is established through coil BKC which closes the switches BK and energizes the alternating current magnet B to release the brake, when the motor is started. When the car reaches the brake leveling control device 30, however, the switch 31 is closed to establish a circuit through coil BLC which opens the switch BL, thus deenergizing coil EKG and hence the brake magnet B and setting the brake. In practice, as above stated, the switch 31 will close sufiiciently in advance of the opening of the switch 28 or 29 '3 to permit the brake to engage the drum at substantially the same moment that the motor circuit is broken.

When the car is within the leveling zone and traveling downwardly toward the floor with the car switch in neutral position the switches DL and DL' will be closed by the operation of the floor leveling device and the car will be stopped in the same manner as when traveling upwardly.

In starting away from a fioor, a circuit is established through the coil FC and either the coil UC or the coil DC through the medium of the car switch 20. The coil FC, thus energized, opens the switch F to cut out the leveling device and at the same time closes the switch F to energize the coil EKG and release the brake regardless of the position of the switch BL.

If the operator should move the car switch to neutral position at such a time that the car stops after the brake leveling control switch 31 closes and before the leveling switch 28 (or 29) opens, the motor M will remain energized but no power will be supplied to the brake magnet B, because coil BLC will remain energized, switch BL, as well as switch F, will remain open, and coil BKC will not be energized. Under such conditions a switch BL, which is closed when coil BLC is energized, will close a circuit through a timed relay coil TRC. This timed relay after the lapse of a predetermined time, say V second, will close a time switch TR which lay-passes the open switch BL and, since the switch UL (or BL) is still closed, a circuit will be established through coil BKC to close the switches BK and operate the brake magnet B to release the brake. The time delay in the operation of the switch TR must be long enough so that if the car is leveling from a distance greater than the distance from the floor to the point where the switch 31 closes, the switch TR will not be closed while the car is moving from the point where the switch 31 closes to the point where the switch 28 (or 29) opens.

While I have shown and described in detail only one specific adaptation of the invention, it will be obvious that the same may be incorporated in any standard electric elevator installation without departing from the scope of the invention as defined in the appended claims.

What I claim is:--

1. In an electric elevator system, the combination with an elevator car, a hoisting motor therefor, a brake normally set, and a brake releasing electromagnet, of a motor control circuit including a switch, a floor leveling circuit bypassing said switch, means for maintaining a circuit through the brake releasing magnet, means for automatically opening the floor leveling circuit as the elevator passes a predetermined point, means to open the circuit through the brake releasing magnet ahead of the opening of the floor leveling circuit, and a time delayed relay, operable to energize the brake releasing magnet it the car stops after the opening of said circuit through the brake releasing magnet and before the floor leveling circuit has been opened.

2. In an electric elevator system, the combination with an elevator car, a hoisting motor therefor, a brake normally set, and a brake releasing electromagnet, of control means for completing circuits through the motor and the brake releasing magnet to move the car up or down, means automatically effective, when the car is within a predetermined zone, to maintain circuits through the motor and the brake releasing magnet independent of said control means, means for aunot tomatically opening the independent circuit through the motor as the car passes a predetermined point, means to open the independent circuit through the brake releasing magnet ahead of the independent circuit through the motor, and a time delayed relay operable to energize the brake releasing magnet if the car stops after the opening of said circuit through the brake releasing magnet and before the floor leveling circuit has been opened.

3. In an electric elevator system, the combination with an elevator car, a hoisting motor therefor, a brake normally set, and a brake releasing electromagnet, of a motor control circuit including a switch, a floor leveling circuit bypassing said switch, means for maintaining a circuit through the brake releasing magnet, means for automatically opening the floor leveling circuit as the elevator passes a predetermined point, means to open the circuit through the brake releasing magnet early enough so that the brake begins to exert its full retarded effect upon the movement or the elevator car at substantially the same instant that the floor leveling circuit is opened, and a time delayed relay operable to re-establish a circuit through the brake releasing magnet if the car stops after the same is opened and before the floor leveling circuit has been opened.

4. In an electric elevator system, the combination with an elevator car, a hoisting motor therefor, a brake normally set, and a brake releasing electromagnet, of operating circuits for the motor and the brake releasing magnet, means for automatically closing floor leveling circuits through the motor and the brake releasing magnet whenever the car enters a predetermined leveling zone, separate and independent means for opening the respective floor leveling circuits through the motor and the brake releasing means, and a time delayed relay operable to re-establish a circuit through the brake releasing means Whenever the car stops before reaching a predetermined accuracy range.

5. In an electric elevator system, an elevator car, hoisting means for said car including a reversible electric motor, a car switch for controlling said motor, a brake for said hoisting means, a motor control circuit independent of the car switch, means for automatically applying the brake and opening said independent motor control circuit as the car passes through a predetermined zone approaching a floor, and means including a time delayed relay to release the brake if the car stops before reaching a predetermined accuracy range Within said zone.

6. In an electric elevator system, the combination with an elevator car, hoisting means therefor including a reversible electric motor, a brake for said hoisting means, and electrical means to release the brake, of operating circuits for controlling the operation of the motor and brake releasing means, a floor leveling circuit for the motor independent of the motor operating circuit, means for automatically opening the floor leveling circuit as the car enters a predetermined zone, means automatically actuated in advance of the opening of the floor leveling circuit to initiate the application of said brake, and a time delayed relay operable to restore the operation of the brake releasing means in case the car stops before reaching a predetermined accuracy range Within said zone.

FBITTS. G. AR'WOOD. 

